Archive for September 2012
It’s tempting to think of amoebae as the single, fried-egg-shaped animal cells we learned about in biology at school – and when there’s plenty of food around, that’s pretty much right. But what happens when the food runs out? For the soil-dwelling Dictyostelium discoideum, things get a little weird.
These amoebae usually feed on bacteria and live quite happily as individual cells when food is plentiful. However, when there’s no bacteria around, the amoebae stick together, or ‘aggregate’, to form slug-like super colonies.
The job of these 4 mm ‘slugs’ is to migrate to a good spot, where they transform again, this time into fruiting bodies – tiny hand grenades filled with spore-like cells – that burst, transporting future amoebae to areas where more food is present, starting the cycle all over again.
The hepatitis B virus (HBV) causes potentially life-threatening diseases, including cirrhosis and liver cancer. The virus is transmitted by bodily fluids and is thought to infect around two billion people, causing approximately 600 000 deaths a year.
HBV has at least ten genotypes. Each genotype, which refers to the arrangement of genetic material in a virus, is divided into multiple subgenotypes, each localised to a particular area or population.
In Korea, where HBV infection is endemic, most viruses isolated are from the C2 (HBV/C2) genotype. The big question is, ‘Where did HBV/C2 come from?’ Now, remarkably, a 16th-century mummy is helping scientists solve the mystery.
Biofilms get a pretty bad rep, and rightly so. Colloquially known as ‘slime’, these sticky scaffolds of polysaccharides, proteins and DNA are produced by colonies of bacteria and let them cling to wet surfaces, whether those are crustacean shells, water pipes or artificial cardiac valves.
Bacteria within biofilms are difficult to kill, which makes them a real problem in hospitals. The bacterial colonies are often more resistant to antibiotics than their free-living relatives, perhaps because the biofilm cocoons the bacteria in the centre and prevents drugs from reaching them. Biofilms are also tricky to remove by cleaning and are impervious to many detergents. Once they’re there, you’re kind of stuck with them, if you’ll excuse the pun.
But what if we could harness the adhesive power of biofilms for good? Could we use them to deliver useful molecules or drugs? A group of researchers is working on that very problem, right now.